Classification of electrical installation premises according to electrical safety
Electrical installations are those installations in which electricity is produced, converted and consumed. They are divided into electrical installations up to 1000V and above 1000V.
Electrical rooms are rooms or fenced off (for example, nets) parts of the room, accessible only to maintenance personnel, in which electrical installations in operation are installed. Based on the nature of the environment, premises are divided into the following types:
Dry, in which relative humidity does not exceed 60%. If in such rooms there are no conditions characterizing “hot rooms”, “dusty rooms”, “rooms with a chemically active environment”, they are called normal.
Humid, where vapor or compensating moisture is released only temporarily and in small quantities, and the relative humidity is more than 60%, but not higher than 75%.
Damp, in which the relative air humidity exceeds 75% for a long time.
Particularly damp, in which the relative air humidity is close to 100% for a long time (the ceiling, wall, floor and objects in the room are covered with moisture).
Hot, where the temperature exceeds 30 ◦ C for a long time.
Dusty, in which, due to production conditions, process dust is released in such quantities that it can settle on wires, penetrate inside machines, devices, etc.; dusty rooms are divided into rooms with conductive and non-conductive dust.
A room with conductive floors is a room with metal, earthen, reinforced concrete, brick, etc. floors
Premises with a chemically active environment, where, due to production conditions, vapors are constantly or for a long time contained or deposits are formed that are destructive to the insulation and live parts of electrical equipment.
Premises that pose a risk of electric shock to people are divided into three categories.
Particularly dangerous. Characterized by: special dampness, a chemically active environment, the simultaneous presence of two or more conditions of increased danger.
Particularly dangerous premises are most of the industrial premises, including all workshops of power plants, battery rooms, cable wells, telephone exchange shafts, etc. In these rooms, the operating voltage and local (working) lighting is set to 12V. When using insulating protective equipment in these rooms, you can work with tools and lamps with a voltage of 42 (36) V. Source undervoltage 42 and 12V are, as a rule, special step-down transformers that have high resistance between the primary and secondary windings. They are powered by a 380/220V network and are connected through an RCD (residual current device) to eliminate the danger of electric shock to a person in the event of voltage appearing on the transformer body or when the highest voltage passes to the 42 or 12V winding, the transformer body and one of the terminals (or neutral when three-phase voltage) must be grounded.
In addition, the plugs of the current collectors low voltage should not be suitable for higher voltage sockets.
With increased danger. Characterized by the presence of one of the following features: dampness, high temperature, conductive dust, conductive floors (metal, earthen, reinforced concrete, brick), the possibility of simultaneous human contact with metal structures of buildings connected to the ground, technological devices, mechanisms, on the one hand, and metal housings of electrical equipment - on the other.
Examples of high-risk premises include staircases with conductive floors, metal machining shops, telephone exchange rooms, radio and television workshops, etc. In these rooms the voltage used is 42 (36) V. When using insulating protective equipment in these rooms, you can work with tools and lamps at 220V voltage. In all cases, the housing of pantographs with voltages above 42 (36) V must be grounded or neutralized.
3. Without increased danger. Premises in which there are no conditions of increased or special danger. An example of such premises would be dry, dust-free premises with normal air temperature, with non-conductive floors and without grounded metal structures. In these rooms, 220V voltage is used for tools and lamps.
Classification and characteristics of electrical installations. Classification of electrical receivers (EP). Characteristics of EP. Brief description of load graphs.
Purpose of the lecture:
· consider the classification and characteristics of electrical installations,
· consider the classification and characteristics of electrical receivers;
· consider brief description load schedules (individual EP, group EP).
2.1. Classification and characteristics of electrical installations
The power supply system is connected with the production process through electrical installations and electrical energy receivers.
Electrical installation(ES) - a set of machines, devices, power lines, auxiliary equipment intended for the production, transformation, transmission, accumulation, distribution of electrical energy and its conversion into another type of energy.
According to the PUE, all power plants are divided into power plants up to and above 1 kV. ECs can operate with both isolated and solidly grounded neutrals. Power plants above 1 kV are divided into installations with low and high ground fault currents.
Enlarged, the main part of the ES can be divided into the following groups:
Power general industrial installations;
Converter installations;
Electrothermal installations;
Electric welding installations;
Lighting installations.
General industrial power plants: compressor, ventilation, pumping, etc. Consumers in this group create a uniform and symmetrical load across all three phases. Their power varies widely from units to hundreds of kW. The power factor is quite stable within the range of 0.8 ÷ 0.85. In terms of reliability of power supply, they should be classified as power receivers of the 1st category.
Converting power plants designed to convert three-phase alternating current to constant, converting industrial frequency 50 Hz into currents with a frequency different from 50 Hz. Consumers of this group create a load on the primary voltage side that is symmetrical and uniform across all three phases. Their power varies widely from tens to thousands of kW. The power factor ranges from 0.6 ÷ 0.8. The interruption in power supply to the power plant is mainly associated with a shortage of products. Therefore, they should be classified as category 2 consumers.
Electrothermal EI – arc, induction and resistance furnaces.
Arc furnaces(steel smelting, furnaces for smelting non-ferrous metals, ore-smelting furnaces). The load on the primary voltage side of the step-down transformer is symmetrical and uniform. Their power varies widely from tens to hundreds of thousands of kW. The power factor ranges from 0.7 ÷ 0.8. In terms of reliability of power supply, they should be classified as power receivers of the 1st category.
Induction melting and hardening furnaces (high frequency). Electric receivers of this group represent a symmetrical three-phase load, on the primary voltage side of power transformers. Their power varies widely from tens to hundreds of kW. The power factor ranges from 0.7 ÷ 0.8. The interruption in the power supply to the power plant is mainly due to the undersupply of products. Therefore, in terms of reliability of power supply, they should be classified as power receivers of the 2nd category.
Resistance furnaces. These EPs are made both three-phase and single-phase. Three-phase resistance furnaces create a symmetrical load across the phases. Single-phase furnaces - unsymmetrical load. Their power ranges from units to tens of kW. The power factor can practically be taken as unity. In terms of reliability of power supply, they should be classified as consumers of the 2nd category.
Electric welding units operate on both alternating and direct current.
AC electric welding installations can be three-phase and single-phase. The operating mode is intermittent and short-term. Electric welding installations direct current consist of a converter unit, usually three-phase. The load in the AC supply network is distributed evenly across the three phases, but maintains an uneven load pattern. The power factor of electric welding installations (for manual welding) ranges from 0.3 ÷ 0.5. In terms of reliability of power supply, they should be classified as electrical receivers of the 3rd category.
Electric lighting installations represent a single-phase load. Due to the low power of the electrical receiver and with the correct distribution of the load across phases, the load can be considered symmetrical. The nature of the load is uniform. The power factor depends on the type of light source. In those industries where turning off lighting threatens the safety of people, they use special systems emergency lighting.
2.2. Classification of electrical energy receivers
An electrical energy receiver (ER) is an electrical device designed to convert electrical energy into another type of energy (or electrical energy, but with other parameters).
Specifics technological processes various industries presents certain requirements to characteristics and design electrical receivers and, as a consequence, their wide variety.
All electronic signatures are classified according to various indicators:
According to electrical indicators;
By operating mode;
On reliability of power supply;
On the implementation of protection against environmental influences.
Let us consider in more detail the classification of electrical receivers according to their indicators.
According to electrical parameters
Of all the variety, electrical receivers of power general industrial electrical installations can be divided into:
Three-phase electric current with voltage above 1 kV, frequency 50 Hz;
Three-phase electric current with voltage up to 1 kV, frequency 50 Hz;
Single-phase electric current with voltage up to 1 kV, frequency 50 Hz;
ED operating with a frequency other than 50 Hz;
DC ED.
Electrical installations are a set of machines, apparatus, lines and auxiliary equipment (together with the structures and premises in which they are installed) intended for the production, transformation, transformation, transmission, distribution of electrical energy and its conversion into another type of energy.
By voltage electrical installations are distinguished:
- up to 1000 V ;
- over 1000 V .
By location electrical installations are:
- open or external (installations protected by nets or canopies are considered external);
- closed or internal.
With regard to the danger of electric shock to people and animals, rooms with electrical installations are divided into the following categories:
Premises with increased danger are characterized by the presence in them of one of following conditions, creating an increased danger:
a) dampness or conductive dust;
b) conductive floors;
c) high temperature;
d) the possibility of simultaneous human touch to metal structures of buildings, technological devices, mechanisms, etc. connected to the ground, on the one hand, and to metal housings of electrical equipment, on the other.
- especially dangerous premises characterized by the presence of one of the following conditions:
a) special dampness;
b) chemically active environment;
c) the simultaneous presence of two or more conditions of increased danger.
- premises without increased danger , in which there are no conditions that create increased and special danger.
According to environmental conditions, rooms in which electrical installations are located are divided into the following categories:
- dry premises (relative humidity does not exceed 60%). These are heated premises for service personnel, dormitories, heated warehouses, utility rooms in mechanical repair shops, etc.;
- dusty premises (according to production conditions, dust is released in such quantities that it can settle on wires, penetrate into machines, devices, etc.) - premises for crushing dry concentrated feed, feed mills, warehouses for cement and other bulk non-combustible materials. ;
- wet premises (vapor or condensing moisture is released only temporarily, in small quantities, relative humidity is more than 60%, but does not exceed 75%) - canteens, staircases, residential kitchens, unheated warehouses, etc.;
- raw premises (relative humidity exceeds 75% for a long time) - vegetable stores, milking parlors, dairy, kitchens of public canteens, etc., as well as, in the presence of microclimate installations, cowsheds, calf sheds, pigsties, poultry houses and other livestock buildings;
- especially raw premises (relative air humidity is close to 100%, the ceiling, walls, floor and objects in the room are covered with moisture) - washrooms in workshops, feed shops for the preparation of wet food, greenhouses, greenhouses, as well as outdoor installations under canopies;
- particularly damp rooms with a chemically active environment (at relative air humidity close to 100%, the room constantly or for a long time contains vapors of ammonia, hydrogen sulfide and other gases of non-explosive concentrations, or deposits are formed that corrode the insulation and live parts of electrical equipment). These are warehouses for mineral fertilizers, livestock buildings in the absence of installations for creating a microclimate.
- fire hazardous premises of class P1, for example mineral oil warehouses. The same, class P II, for example woodworking shops, granaries. The same, class P IIa - warehouses for storing flammable materials, livestock buildings when storing hay and straw in attics.
- explosive premises - battery rooms, petroleum product storage facilities, etc.
Depending on the characteristics of the premises and electrical installations that are located in them, to the selection, design and installation of machines, apparatus, devices, as well as to the selection and installation electrical wires and cables are subject to various requirements, the fulfillment of which ensures the reliability and safety of servicing electrical installations.
By flammability building materials structures of buildings and surfaces of premises are divided into the following groups:
1. Fireproof structures, under the influence of fire or high temperature they do not ignite, do not smolder or char.
2. Fire-resistant structures exposed to fire or high temperature are difficult to ignite, smolder or char and continue to burn or smolder only in the presence of a fire source.
3. Combustible structures ignite when exposed to high temperatures and continue to burn or smolder after the fire source is removed.
According to the storage method, electrical equipment is divided into the following groups.
1. Electrical equipment that does not require protection from precipitation must be stored in open areas and overpasses.
2. Electrical equipment that requires protection from direct exposure to precipitation and is insensitive to temperature fluctuations must be stored in semi-open warehouses under common or individual sheds.
3. Electrical equipment and electrical structures that require protection from precipitation and dampness and are insensitive to temperature fluctuations, as well as all small parts, must be stored in closed, uninsulated warehouses.
4. Devices and critical mechanisms that are sensitive to temperature fluctuations must be stored in closed, insulated warehouses.
Electrical equipment (E) and electrical devices (ED) with regard to the protection of personnel from touching live and moving parts and from foreign objects, liquids and dust getting into the equipment (GOST 18311-80*) are divided into the following main types: moisture-resistant, open, protected , waterproof, splash-proof, drip-proof, dust-proof, closed, sealed, explosion-proof.
GOST 14254-80 establishes the characteristics of the degrees of protection of personnel from contact with live or moving parts located inside the shell, as well as the degrees of protection of equipment built into the shell from the ingress of solid foreign bodies and the designation of these characteristics.
Table 1.1 presents classes of electrical products according to the method of human protection.
Table 1.1 Classes of electrical equipment used in electrical installations with voltages up to 1000 V
| Class according to GOST 12.2.007.0 RMEC536 | Design features, markings: | Purpose of protection | Conditions for use in electrical installations |
| Class 0 | There is working insulation and no elements for grounding | With indirect touch | 1. Application in non-conductive areas. 2. Power supply from the secondary winding of the isolation transformer to only one power receiver |
| Class I | There is working insulation and a grounding element. The protective clamp has a sign or the letters PE, or yellow-green stripes | Same | Connecting the grounding clamp to the protective conductor of the electrical installation |
| Class II | There is double or reinforced insulation and no grounding elements. Sign | Same | Regardless of the protective measures taken in the electrical installation |
| Class III | There are no internal or external electrical circuits with voltages higher than 42 V. Sign | From direct and indirect touches | Power supply from safety isolation transformer |
Characteristics of the degrees of protection of electrical equipment shells with voltages up to 1000 V from injury to personnel and from the influence of the external environment are given in Table 1.2.
Table 1.2 Characteristics of degrees of protection of electrical equipment shells with voltages up to 1000 V
| Degree of protection | Characteristics of the degree of protection | |
| personnel from contact with live or moving parts and equipment from foreign solids entering the shell | equipment from water penetration into the shell | |
| 0 | No protection | No protection |
| 1 | Protection against accidental contact of a large area of the surface of the human body with live or moving parts inside the shell. There is no protection against intentional access to these parts. Protection against foreign solid bodies with a diameter of at least 52.5 mm | Protection against drops of condensed water. Drops of condensed water falling vertically onto the shell should not cause harmful effects to the equipment inside the shell |
| 2 | Protection against the possibility of human fingers coming into contact with live parts or inside the shell. Protection against foreign solid bodies with a diameter of at least 12.5 mm | Protection from dripping water. Drops of water falling on an enclosure inclined at an angle of no more than 15° to the vertical shall not have any harmful effect on the electrical equipment in the enclosure |
| 3 | Protection against contact of a tool, wire or other similar objects whose thickness exceeds 2.5 mm with live or moving parts inside the enclosure. Protection against foreign bodies with a diameter of at least 2.5 mm | Rain protection. Rain falling on an enclosure inclined at an angle of not more than 60° to the vertical shall have no harmful effect on the equipment within the enclosure. |
| 4 | Protection against contact of a tool, wire or other objects whose thickness exceeds 1 mm with live parts inside the shell. Protection against foreign bodies with a diameter of at least 1 mm | Splash protection. Splashes of water from any direction falling on the enclosure shall not have any harmful effect on the equipment inside the enclosure. |
| 5 | Complete protection of personnel from contact with live or moving parts located inside the enclosure. Protection against dust deposits | Protection against water jets. Water projected through the tip onto the enclosure in any direction shall not have any harmful effect on the equipment in the enclosure. |
| 6 | The same goes for complete protection of equipment from dust. | Protection from the elements typical of a ship's deck (including deck waterproof equipment) |
| 7 | - | Protection when immersed in water. Water must not penetrate the enclosure at the pressure and time specified in the equipment standards or specifications |
| 8 | - | Protection against unlimited immersion in water. Water must not penetrate the enclosure at the pressure specified in the standard or specification |
The designations of the degrees of protection of the shells of devices are given in Table 1.3, electrical machines in Table 1.4.
The symbol for the degree of protection contains the following data:
IP - the first letters of the English words International Protection, denoting protection according to international standards;
The first digit indicates the degree of protection against contact and ingress of foreign bodies;
The second digit indicates .
Table 1.3 Symbols for degrees of protection of shells of electrical devices with voltages up to 1000 V
Degree of protection against water penetration |
|||||||||
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | |
| 0 | IP00 | ||||||||
| 1 | IP10 | IP11 | IP12 | ||||||
| 2 | IP20 | IP21 | IP22 | IP23 | |||||
| 3 | IP30 | IP31 | IP32 | IP33 | IP34 | ||||
| 4 | IP40 | IP41 | IP42 | IP43 | IP44 | ||||
| 5 | IP50 | IP51 | IP54 | IP55 | IP56 | ||||
| 6 | IP60 | IP65 | IP66 | IP67 | IP68 | ||||
Table 1.4 Symbols for degrees of protection of electrical machines with voltages up to 1000 V
| Degree of protection against contact and ingress of foreign bodies | Degree of protection against water penetration |
||||||||
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | |
| 0 | IP00 | IP01 | |||||||
| 1 | IP10 | IP11 | IP12 | IP13 | |||||
| 2 | IP20 | IP21 | IP22 | IP23 | |||||
| 4 | IP43 | IP44 | |||||||
| 5 | IP54 | IP55 | IP56 | ||||||
Example: an enclosure of electrical equipment that protects personnel from the possibility of contact of fingers with live or moving parts of electrical equipment, which protects the equipment from solid bodies with a diameter of at least 12.5 mm and from rain falling on the enclosure at an angle of no more than 60° to the vertical, is designated IP23 .
In GOST 18311-80* for individual species electrical equipment and electrical devices, the following corresponding degrees of protection are named according to GOST 14254-80:
Open - IP00;
Protected - with all degrees of protection except IP00;
Waterproof - IP55, IP65, IP56, IP66;
Splash-proof - IP34, IP44, IP54;
Drop-proof - IP01, IP11, IP21, IP31, IP41, IP51, IP12, IP22, IP32, IP42, IP13, IP23, IP33, IP43;
Dustproof - IP50, IP51, IP54, IP55, IP65, IP66, IP67, IP68;
Sealed - IP60, IP65, IP66, IP67, IP68.
The cooling method of an electric machine is indicated by the IC (International Cooling) symbol and numbers.
Electrical machines with degrees of protection IP54 and IP44 are produced with the cooling method IС0141.
The first two digits (01) determine that the outer surface of the machine is blown by a fan mounted on the machine shaft and cooling the machine with ambient air through its shell. The next two numbers (41) refer to the inside of the machine and mean that the air inside the machine is driven by the rotor itself or an additional internal fan, and heat is transferred inside the machine environment through the surface of the bed, which can be smooth or ribbed.
The cooling method of IC0041 differs from the previous one in the absence of an external fan. With the IC0151 cooling method, heat is exchanged between the air inside and outside the machine using a built-in cooler. Cooling method IC01 is available in IP23 machines.
Objects erected to meet the material and cultural needs of society are called structures. Based on geometric characteristics, they are all divided into volumetric (buildings of all types and purposes), site (sports grounds, warehouse areas) and linear (roads, overhead power lines, external pipelines).
Structures located above the planning mark of the territory are called above-ground (overpasses, overpasses, towers), below the planning mark - underground (basements, cable lines) and deep (wells, boreholes).
A significant part of the structures are buildings, which, as a rule, are characterized by the presence of premises necessary for human activities. Based on their purpose, buildings are divided into residential, public, industrial, agricultural and warehouse. Public buildings include children's institutions, educational, shopping, medical, cultural, sports institutions, etc.
SNiP also provides for the classification of buildings and structures depending on the number of floors: industrial building are divided into one-story and multi-story, civil - into one-story, low-rise (2 or 3 floors), multi-story (up to 10 floors) and high-rise (more than 10 floors).
According to the type of material of external walls, they are distinguished stone buildings(from natural or artificial stone), wooden and mixed.
Based on the type of load-bearing frame, buildings with load-bearing external and internal walls, frame and combined (for example, box-shaped with load-bearing external walls and an internal frame) are distinguished.
Any building or structure consists of structural elements, performing certain functions. The main ones are the foundation, walls, supports, floors, roof, partitions, stairs, windows, lanterns and doors.
Foundation - This is an underground structure that receives loads from the building and transfers them to the base, i.e. ground. The plane on which the foundation rests on the ground is called the base, and the distance from the base to the surface of the earth is called the depth of the foundation.
Walls separate the premises from external space(external) or from neighboring rooms (internal). They can be bearing , taking, in addition to its own weight, the load from the floors and roof and transferring it to the foundation; self-supporting , taking their own weight and load from the wind and transferring this load to the foundation; non-structural , resting on the frame and supporting its own weight within one floor. A fire-resistant and, as a rule, blank wall is called firewall.
Supports are called pillars or columns that support the floors and roof (and sometimes walls) and transfer the loads from them to the foundation.
Floors are called structures that divide a building by height. They receive and transmit the loads falling on them to the walls or supports and, in addition, provide the spatial rigidity of the building. Depending on the installation location, ceilings can be basement, interfloor and attic.
Roof serves as the top fence of a building or structure, protecting it from external atmospheric influences. The waterproof membrane of a roof is called roof , and the space between the roof and the attic floor is attic . In modern construction attic floor often combined with a roof, and then this design is called a roofless roof, or a combined roof.
Partitions - This interior walls dividing the floor into separate rooms. Just like walls, they can be load-bearing or non-load-bearing, depending on the nature of the perceived load.
Stairs serve for communication between floors and, as a rule, are located in rooms enclosed by walls - staircases.
Window intended for natural light premises and their ventilation. If there are not enough windows for lighting and ventilation of a room (an art gallery or a workshop with dusty production), lanterns - large openings with glazed movable frames.
Doors serve for communication between rooms (internal) or between rooms and outdoor space (external). In industrial, warehouse and other buildings for the delivery of equipment and materials, gates .
The building may also include other elements - a porch, a balcony, etc.
When designing buildings and structures, artificial lighting and various sanitary devices are provided to provide heating, ventilation, air conditioning, gas supply, hot and cold water supply, sewerage, etc.).
Nowadays, it is almost impossible to imagine any area of industry without the use of electricity. We are well aware of some areas of the use of electrical energy, but have a rather vague idea of others. How many of us can answer the question “What is an electrical installation and where is it used?”
What is an electrical installation
An electrical installation is a group of electrical equipment that is interconnected and located on the same territory or area. An electrical installation can rightfully be considered various kinds equipment and tools, lines and machines with which the following types of operations are performed:
- Conversion;
- Transformation;
- Distribution;
- Conversion, etc.
With the participation of various types of electrical equipment and tools, the transformation of one type of electrical energy into another occurs. Their operation is impossible without the participation of electrical energy, which is supplied as a result of the action of switching equipment.
Classification of electrical installations
The location of electrical equipment and electrical installations in a room in general is determined by several factors:
Electrical installations are divided among themselves according to power:
- Up to 1000 V. Used to ensure the operation of equipment with power up to 1000 V;
- From 1000 to 1500 V. They are used to supply direct current from the power source to its consumers no more than 1500 V.
By type of use, eclectic installations are divided into the following types:
- Electric stations. Used to ensure the operation of electrical industrial equipment and the functioning of heat supply lines;
- High power water heaters. Designed for heating large quantity water;
- Lighting systems. Provide electrical supply to private and country houses.
Precautions when using electrical installations
In order to avoid electric shock, it is necessary to observe certain safety measures when working with electrical installations:
- It is prohibited to carry out repairs or maintenance on electrical installations that are switched on;
- In case of direct contact with electrical equipment or wires, it is necessary to use special devices (rubber gloves, special tool with rubberized handles, rubber mats and galoshes);
- To carry out work with electrical installations, you must undergo special training and have permission to work with them.
It is best not to carry out the work yourself, but to seek the help of a specialist.
These rules are mandatory for all electricity consumers, regardless of their departmental affiliation. These rules apply to existing electrical installations of consumers.
What does the term "electrical safety" mean?
Electrical safety is a system of organizational and technical measures and means that ensure the protection of people from the harmful and dangerous effects of electric current, electric arc, electromagnetic field and static electricity.
What does the term electrical installation mean?
Electrical installations are a set of machines, apparatus, lines and auxiliary equipment (together with the structures and premises in which they are installed) intended for the production, transformation, transformation, transmission, distribution of electrical energy and its conversion into another type of energy. Electrical installations, according to electrical safety conditions, are divided into electrical installations with voltages up to 1000 V and electrical installations with voltages above 1000 V. The electrical installation of a building is a set of interconnected electrical equipment within the building.
Which electrical installations are considered operational? Classification of electrical installations by voltage?
Operating electrical installations are considered to be those installations that contain sources of electricity (chemical, galvanic and semiconductor elements) that are fully or partially energized or to which voltage can be applied at any time by turning on switching equipment. According to electrical safety conditions, electrical installations are divided into electrical installations with voltages up to 1000 V inclusive and electrical installations with voltages above 1000 V.
Describe electrical premises.
Electrical rooms are rooms or parts of a room fenced off, for example, with nets, accessible only to qualified service personnel, in which electrical installations are located. Dry rooms are rooms in which the relative air humidity does not exceed 60%. Wet rooms - the relative air humidity in them is more than 60%, but does not exceed 75%. Damp rooms - the relative air humidity in them exceeds 75% for a long time. Particularly damp - relative air humidity is close to 100%. Hot – the temperature in them exceeds constantly or periodically (more than 1 day) +35°C. In dusty rooms, due to production conditions, process dust is released in such quantities that it can settle on wires and penetrate into machines and devices. In rooms with a chemically active or organic environment, aggressive vapors, gases, liquids are constantly or for a long time contained, deposits or mold are formed that destroy the insulation of electrical equipment.
What categories are premises divided into regarding the danger of electric shock to people?
With regard to the danger of electric shock to people, they distinguish: Premises without increased danger, in which there are no conditions that create increased or special danger. Premises with increased danger, which are characterized by the presence of one of the following conditions that create increased danger: - dampness, - conductive dust, - conductive floors (metal, earthen, reinforced concrete, brick, etc.), - heat, - the possibility of simultaneous human touch to metal structures connected to the ground, technological devices, on the one hand, and to metal housings of electrical equipment, on the other. Particularly hazardous premises, which are characterized by the presence of one of the following conditions that create a special danger: special dampness, a chemically active or organic environment, or two or more conditions of increased danger at the same time. In terms of the danger of electric shock to people, the areas where outdoor electrical installations are located are equated to particularly dangerous premises.
Zeroing, purpose and principle of operation.
Grounding is the intentional electrical connection to the neutral protective conductor of metal non-current-carrying parts that may be energized due to a short circuit to the housing and for other reasons. The purpose of grounding is to eliminate the danger of electric shock in the event of touching the body and other non-current conductors. metal parts electrical installations that are energized due to a short circuit to the housing. This problem is solved in a different way than with protective grounding: by quickly disconnecting the damaged electrical installation from the network. However, since the housing is grounded through the neutral protective wire, then during an emergency period, i.e. from the moment a short circuit to the housing occurs and until the installation is disconnected from the network, the protective property of this grounding manifests itself in the same way as is the case with protective grounding. The operating principle of grounding is the transformation of a short circuit to the housing into a single-phase short circuit (i.e. a short circuit between the phase and neutral wires) in order to cause a large current that can ensure the protection is triggered and thereby automatically disconnect the damaged installation from the supply network. Such protection is: fuses or maximum circuit breakers installed in front of electricity consumers to protect them from currents short circuit; magnetic starters with built-in thermal protection, contactors designed for remote starting and stopping of electric motors in combination with a thermal relay, protecting the consumer from overload; and, finally, circuit breakers with combined releases that simultaneously protect consumers from short-circuit currents and overloads. The scope of application of grounding is three-phase four-wire networks up to 1000 V with a solidly grounded neutral. Typically these are 380/220 V and 220/127 V networks, as well as 660/380 V networks.
Which conductor is called protective?
A protective conductor (PE) in electrical installations is a conductor used to protect people and animals from electric shock. In electrical installations up to 1000 V, the protective conductor connected to the solidly grounded neutral of the generator or transformer is called the neutral protective conductor.
Which conductor is called zero worker?
The neutral working conductor (N) in electrical installations up to 1000 V is the conductor used to power electrical receivers, connected to the half-grounded neutral of a generator or transformer in three-phase current networks, to a solidly grounded terminal of a single-phase current source, to a solidly grounded source point in three-wire DC networks.
For what purpose should grounding devices be constructed and metal parts of electrical equipment grounded?
To ensure the safety of people in power plants with an insulated netal, in accordance with the requirements of the Electrical Installation Rules, grounding devices must be constructed to which electrical equipment enclosures are reliably connected, which may become energized due to insulation failure.
Which parts of electrical installations and electrical equipment are subject to grounding or grounding?
Parts subject to grounding or grounding include: - housings of electrical machines, transformers, devices, lamps, etc.; - drives of electrical devices; - secondary windings of instrument transformers; - frames of distribution boards, control panels, panels and cabinets; - metal structures of switchgears, metal cable structures, metal casings of cable couplings, metal shells and armor of control and power cables, metal sheaths of wires, steel pipes electrical wiring and other metal structures associated with the installation of electrical equipment; - metal cases of mobile and portable electrical receivers.
Protective grounding, purpose and scope?
Purpose and scope. Protective grounding is the intentional electrical connection to the ground or its equivalent of metal non-current-carrying parts that may be energized due to a short circuit to the body and for other reasons (inductive influence, potential removal), etc. A short-circuit to the body, or more precisely an electrical short-circuit to the body, is an accidental electrical connection of a current-carrying part with metal non-current-carrying parts of an electrical installation. A short-circuit to the housing can result, for example, from: accidental contact with a live part of the machine body, damaged insulation, falling of a live wire onto the specified metal non-current-carrying parts, etc. The purpose of protective grounding is to eliminate the danger of electric shock in the event of touching the housing and other non-current-carrying metal parts of an electrical installation that are energized. The scope of application of protective grounding is three-phase networks up to 1000 V with an insulated neutral and above 1000 V in any neutral mode. Protective grounding should be distinguished from the so-called working grounding - intentional electrical connection with ground of individual points electrical network(for example, neutral point, phase conductor, etc.) necessary for proper operation of the installation under normal or emergency conditions. Working grounding is carried out directly or through special devices - breakdown fuses, arresters, resistors, etc.
What are the rules for installing grounding?
Ground connections are installed on the current-carrying part immediately after checking the absence of voltage. The portable grounding is first connected to the grounding device, and then, after checking that there is no voltage, it is installed on live parts. The portable grounding is removed in the reverse order; first from live parts, and then disconnected from the grounding device. Installation and removal of portable grounding is carried out wearing dielectric gloves and using an insulating rod in electrical installations above 1000 V. The portable grounding clamps are secured with the same rod or directly with hands wearing dielectric gloves. It is prohibited to use conductors for grounding that are not intended for this purpose, as well as to connect grounding connections by twisting them. It is allowed, in cases where the cross-section of the cable cores does not allow the use of portable grounding, for electric motors up to 1000V it is necessary to ground the cable line with a copper conductor with a cross-section not less than the cross-section of the cable cores or connect the cable cores together and insulate them. Such grounding or connection of cable cores is taken into account in operational documentation along with portable grounding.
How are grounding and neutral protective conductors connected?
The connection of grounding and neutral protective conductors to grounding conductors, the grounding loop to grounding structures is carried out by welding, and to the housings of devices, MACHINES and overhead line supports - by welding or reliable bolted connection. Each part of the electrical installation to be grounded or grounded is connected to the grounding or grounding network using a separate conductor. The sequential connection of grounded or neutralized parts of an electrical installation to the grounding or neutral protective conductor is prohibited. Grounding and neutral protective conductors must have a coating that protects them from corrosion.
How are electrical receivers carried out? grounding or grounding of portable
Grounding or grounding of portable electrical receivers is carried out by a special conductor (the third - for single-phase and direct current electrical receivers, the fourth - for three-phase current electrical receivers), located in the same shell with the phase conductors of the portable wire and connected to the “body” of the electrical receiver and to a special contact of the plug connection. The cross section of this core should be equal to the section phase conductors. The use of a neutral working conductor for this purpose, including one located in a common shell, is not permitted. The conductors of wires and cables used for grounding or neutralizing portable electrical receivers must be copper, flexible, with a cross-section of at least 1.5 mm square. for portable electrical receivers in industrial installations and not less than 0.75 mm sq. for household portable power receivers.
What are electrical protective equipment?
Electrical protective equipment includes: - insulating rods of all types (operational, measuring, for applying grounding); - insulating and electrical clamps; - voltage indicators of all types and voltage classes (with a gas-discharge lamp, non-contact, pulse type, with an incandescent lamp, etc.); - non-contact voltage detectors; - isolated tool; - dielectric gloves, boots and galoshes, carpets, insulating stands; - protective barriers (shields, screens, insulating linings, caps); - portable grounding; - devices and devices to ensure occupational safety when carrying out measurement tests in electrical installations (voltage indicators for checking phase coincidence, devices for piercing a cable, a device for determining the voltage difference in transit, cable damage indicators, etc.), - posters and signs security; - other protective equipment, insulating devices and devices for repair work at voltages of 110 kV and higher, as well as in electrical networks up to 1000 V (polymer and flexible insulators; insulating ladders, ropes, inserts of telescopic towers and lifts; rods for transfer and potential equalization; flexible insulating coatings and linings, etc.).
What is the main electrical protective agent?
The main electrical protective agent is an insulating electrical protective agent, the insulation of which can withstand the operating voltage of the electrical installation for a long time and which allows you to work on live parts that are energized. Basic electrical protective equipment is made from insulating materials(porcelain, ebonite, getinaks, wood-laminated plastics, etc.). Materials that absorb moisture (bakelite, wood, etc.) must be coated with moisture-resistant varnish and have smooth surface no cracks, peeling or scratches.
What applies to electrical installations above 1000 V? basic electrical protective equipment in
The main electrical protective equipment in electrical installations with voltages above 1000 V include: - insulating rods of all types; - insulating and electrical clamps; - voltage indicators; - devices and devices to ensure occupational safety when carrying out tests and measurements in electrical installations (voltage indicators for checking phase coincidence, devices for cable puncture, cable damage indicators, etc.); - other protective equipment, insulating devices and devices for repair work under voltage in electrical installations with voltages of 110 kV and above (polymer insulators, insulating ladders, etc.)
What are the main electrical protective equipment in electrical installations up to 1000 V?
The main electrical protective equipment and electrical installations with voltages up to 1000 V include: - insulating rods; - insulating and electrical clamps; - voltage indicators; - dielectric gloves; - isolated tool.
What is an additional electrical protective agent?
An additional electrical protective agent is an insulating electrical protective agent, which itself cannot provide protection against electric shock at a given voltage, but complements the main protective agent and also serves to protect against touch voltage and step voltage.
What applies to additional electrical protective equipment in electrical installations above 1000 V?
Additional electrical protective equipment in electrical installations with voltages above 1000 V include: - dielectric gloves; - dielectric boots; - dielectric carpets; - insulating supports and covers; - insulating caps.
What applies to additional electrical protective equipment for electrical installations up to 1000 V?
Additional electrical protective equipment for electrical installations up to 1000 V include: - dielectric galoshes; - dielectric carpets; - insulating supports and covers; - insulating caps.
How are posters and safety signs classified?
Posters and safety signs are used to: - prohibit actions with switching devices (prohibiting); in c - warning about the danger of approaching live parts that are energized (warning); - permission certain actions only when specific labor safety requirements are met (warning), - indications of the location of various objects and devices (indicative). Prohibiting: "DO NOT TURN ON! PEOPLE ARE WORKING." "DO NOT TURN ON! WORK ON THE LINE", "DO NOT OPEN! PEOPLE ARE WORKING", "DANGEROUS ELECTRIC FIELD WITHOUT PROTECTION MEANS, PASSAGE IS PROHIBITED", "WORK UNDER VOLTAGE DO NOT TURN ON AGAIN." Warning: sign "CAUTION! ELECTRIC VOLTAGE" and posters "STOP! VOLTAGE", "TEST DANGEROUS TO LIFE", DO NOT ENTER! WILL KILL." Prescriptive: "WORK HERE", "GET IN HERE". Index: "GROUNDED".
What is the procedure for maintaining and storing electrical protective equipment in electrical installations with voltages up to and above 1000 V?
Electrical protective equipment in use and in stock must be stored and transported under conditions that ensure their serviceability and suitability for: use without prior repair, therefore protective equipment must be protected from moisture, contamination and mechanical damage. Electrical protective equipment made of bakelite, plastic materials, ebonite, wood should be stored in indoors. Electrical protective equipment made of rubber that is in use must be stored indoors, in special cabinets, on racks, in boxes, etc., separately from the tool. They must be protected from exposure to oils, gasoline, direct exposure sun rays. Spare electrical protective equipment made of rubber should be stored in a heated, dark, dry room at a temperature of O...5°C. Insulating rods are stored in a vertical position, suspended or installed in risers without contact with the wall. The rods can be stored horizontally. In this case, the possibility of their deflection should be excluded. Insulating clamps are stored on special shelves so that they do not touch the walls. Voltage indicators and electrical clamps should be stored in cases. Insulating devices and devices for working under voltage: insulating ladders, platforms and other similar devices are stored in certain places where they are protected from moisture and dust.
What are the general rules for using electrical protective equipment used in electrical installations with voltages up to and above 1000 V?
Electrical protective equipment is used for its intended purpose in electrical installations with a voltage no higher than that for which they are designed. All basic electrical protective equipment is designed for use in closed or open distribution devices and on air lines only in dry weather. Therefore, the use of these funds for outdoors and in wet weather (during rain, snow, frost, fog) is prohibited. In this case, specially designed tools are used that are designed to work in such conditions. Before each use of an electrical protective device, personnel are obliged to: - check its serviceability and absence of external damage, clean and wipe off dust, check rubber gloves for punctures; - check the stamp for what voltage is acceptable for use this tool and whether the period of periodic testing has expired. The use of protective equipment whose testing period has expired is prohibited, since such equipment is considered unsuitable.
What is the damaging effect of electric current on the human body?
The biological effect of electric current on the human body under voltage is manifested in convulsive contraction of various muscle groups, including the muscles that carry out the respiratory movement of the chest and regulate the functioning of the heart. The greatest danger is a violation of cardiac activity due to the occurrence of cardiac fibrillation, which is characterized by multi-temporal uncoordinated contraction of individual fibers of the heart muscle, leading to disruption of the rhythmic contraction of the heart OR even to its paralysis. The type of electric shock to a person, in which breathing is disrupted and the heart does not pulsate, is called an electric shock. The degree of physiological impact of electric current is mainly determined by its type and magnitude, duration of flow and depends on the path of the current through the human body and the individual properties of the person. The most likely path is arm-arm, arm-leg, leg-leg. In addition, damage can occur without direct current passing through the human body as a result of burns caused by an open electric arc.
What voltage is considered dangerous to human life? What amount of current is considered fatal to a person?
There is still no established point of view regarding the amount of “permissible” or “safe” voltage, since electrical resistance person varies widely depending on specific conditions. That's why various countries regulate their own standards. For example, in France the standard is 24 V for AC and 50 V for DC. In our practice, depending on the environmental conditions, the permissible voltage is up to 50 V AC. However, these voltages cannot be considered as providing complete safety. For example, the literature describes cases of fatal injury to a person with a voltage of 12 V and below. The dangerous value of current flowing through the human body should be considered 10 mA, lethal - 100 mA.
What types of burns are there?
Burns can be thermal - caused by fire, steam, hot objects and substances, chemical - by acids and alkalis, and electrical - by exposure to electric current or electric arc. According to the depth of damage, all burns are divided into four degrees: - first - redness and swelling of the skin; - second - water bubbles; - third, necrosis of the superficial and deep layers of the skin; - fourth - charring of the skin, damage to muscles, tendons and bones.
What determines the danger to a person when electric current passes through him?
The magnitude of the current passing through the body, the time a person spent under the electric current, the frequency of the current, the individual properties of the person.
What is the sequence of first aid for electric shock victims?
The sequence of first aid is as follows: - eliminate the impact on the body of damaging factors that threaten the health and life of the victim (free from electric current, extinguish burning clothing, etc.), assess the condition of the victim; - determine the nature and severity of the injury, the greatest threat to the life of the victim and the sequence of measures to save him; - carry out the necessary measures to save the victim in order of urgency (restore airway patency, perform artificial respiration, external cardiac massage, stop bleeding, etc.); - support the victim’s basic vital functions until arrival medical worker; - call an ambulance or a doctor or take measures to transport the victim to the nearest medical facility. Saving a victim from the action of electric current in most cases depends on the speed of releasing him from the current, as well as on the speed and correctness of providing him with assistance. Delay in filing it may result in the death of the victim.
What types of electric shock are there?
Electric shock causes damage to human internal organs (heart paralysis, respiratory paralysis); electrical injuries, damage to external parts of the body.
What are the rules for freeing a victim from electric shock?
If the victim comes into contact with live parts, it is necessary, first of all, to free him from the action of electric current. It should be borne in mind that touching a live person without taking proper precautions is dangerous to the life of the person providing assistance. Therefore, the first action of the person providing assistance should be to quickly turn off the part of the installation that the victim is touching. In this case, it is necessary to take into account the following: - if the victim is at a height, turning off the installation and freeing him from electric current can lead to the victim falling from a height, therefore measures must be taken to ensure the safety of the victim’s fall; - when the installation is turned off, the electric lighting may also turn off at the same time, in connection with which lighting should be provided from another source, without, however, delaying the shutdown of the installation and the provision of assistance to the victim. If the installation cannot be switched off quickly enough, measures must be taken to separate the victim from live parts that he touches. In this case, you should use dry clothes, a rope, a stick, a board or some other dry object that does not conduct electric current. The use of metal or wet objects for these purposes is not permitted. When separating a victim from live parts, it is recommended to act with one hand whenever possible. To separate the victim from the ground or live parts energized above 1000V, you should wear dielectric gloves and boots and use a rod or pliers designed for the voltage of a given electrical installation.
How is first aid provided to an electric shock victim?
First aid measures depend on the condition in which the victim is. To determine this condition, it is necessary to immediately carry out the following measures (time no more than 1 minute): - lay the victim on his back on a hard surface; check if the victim is breathing (determined by the rise of the chest); - check the victim’s pulse; - find out the condition of the pupil (narrow or wide) - a wide pupil indicates a sharp deterioration in blood supply to the brain. In all cases of electric shock, calling a doctor is mandatory, regardless of the condition of the victim. If it is not possible to quickly call a doctor, it is necessary to urgently deliver the victim to a medical facility and provide the necessary vehicles or stretchers for this. In case of electric shock, the victim may be conscious or unconscious. If the victim is conscious, he should be placed in a comfortable position and ensure complete rest until the doctor arrives. If the victim is unconscious, then you should immediately unbutton your clothes, create an influx of fresh spirit, and let him smell ammonia, spray him with water and perform artificial respiration.
How is artificial respiration (pulmonary ventilation) performed?
Artificial respiration is carried out in cases where the victim does not breathe or breathes very poorly (rarely, convulsively, as if sobbing), and also if his breathing is constantly deteriorating. Most effective way artificial respiration is a “mouth-to-mouth” or “mouth-to-nose” method, since this evaluates the supply of a sufficient volume of air to the victim’s lungs. Air is blown through gauze, a scarf, special device- air duct. The victim is placed on his back, his clothes are unbuttoned, the upper respiratory tract, which is closed by a sunken tongue, is ensured, and the oral cavity is freed from foreign bodies. The person providing assistance leans towards the victim’s face and takes a deep breath. open mouth, completely tightly covers the victim’s open mouth with his lips and exhales vigorously, blowing air into his mouth with some effort, while at the same time he covers the victim’s nose with his cheek or fingers. In this case, it is imperative to observe the victim’s chest, which rises. As soon as the chest rises, the air injection is stopped, the person providing assistance turns his face to the side, and the victim exhales passively. If the victim’s pulse is well determined and only artificial respiration is necessary, then the interval between artificial breaths is 5 s. (12 breathing cycles per minute). For small children, air is blown into the mouth and nose at the same time, covering the child’s nose with their mouth. How smaller child, the less air he needs to inhale and the more often he should inflate compared to an adult (up to 35.18 times per minute). Stop artificial respiration after the victim has restored sufficiently deep and rhythmic spontaneous breathing.
How is external cardiac massage performed?
In case of electric shock, not only breathing may stop, but blood circulation will also stop when the heart does not circulate blood through the vessels. In this case, artificial respiration alone when providing assistance is not enough: since oxygen from the lungs cannot be transferred by the blood to other organs and tissues, it is necessary to resume blood circulation artificially. If you press on the sternum, the heart will be compressed between the sternum and the spine and blood will be squeezed out of its cavities into the vessels. If you press on the sternum with jerking movements, the blood will be pushed out of the cavities of the heart in almost the same way as it happens during its natural contraction. This is called external cardiac massage, in which blood circulation is artificially restored. Thus, when artificial respiration is combined with external cardiac massage, the functions of breathing and circulation are imitated. The complex of these measures is called resuscitation, and the measures are called resuscitation.
What are the conditions for using portable power tools and hand-held electrical machines in various rooms?
In rooms without increased danger and in rooms with increased danger, the use of class I equipment is allowed under the following conditions: - the use of at least one of the electrical protective equipment (dielectric gloves, carpets, stands, galoshes); - without the use of electrical protective equipment, if the machine or tool has only one electrical receiver, receives power from an isolation transformer, an autonomous motor-generator set, a frequency converter with separate windings or through an RCD; - class II, III - without the use of electrical protective equipment. In particularly dangerous premises, outdoors (external work), equipment of class I is not allowed, equipment of class II, III is allowed to be used without electrical protective equipment. If there is special unfavorable conditions(in vessels, apparatus and other metal containers with limited opportunity movement and exit) equipment of class I is not allowed to be used, equipment of class II is allowed to be used using one of the electrical protective equipment (dielectric gloves, carpets, stands, galoshes), as well as without the use of electrical protective equipment, if the machine or tool has only one electrical receiver , receives power from an isolation transformer, an autonomous motor-generator set, a frequency converter with isolation windings or through an RCD, class III equipment - without the use of electrical protective equipment.
At what voltage should a portable power tool be used?
Portable power receivers should be powered from a network with a voltage not exceeding 380/220 V. Depending on the category of the room in terms of the level of danger of electric shock to people, portable power receivers can be powered either directly from the network, or through isolating or step-down transformers. Metal housings of portable electrical receivers with voltages above 50 V AC and above 60 V DC in all indoor and outdoor installations must be grounded or neutralized, with the exception of electrical receivers with double insulation or powered by isolation transformers.
What should people using power tools not do?
Persons who use power tools and hand tools electric machines, it is prohibited: - to transfer hand-held electric machines and power tools, at least temporarily, to other persons; - disassemble hand-held electric machines into power tools and carry out any repairs themselves (both the power tool itself or the hand-held electric machine, and the wires of plug connections, etc.); - hold onto the wire of a hand-held electrical machine or power tool or touch a rotating cutting tool; - remove shavings or sawdust by hand while working until the manual electric machine comes to a complete stop; - work from ladders; to perform work at height, strong scaffolding or scaffolding must be installed; - carry into boiler drums, metal tanks, etc. portable transformers and frequency converters; - leave hand-held electrical machines and power tools unattended and plugged in.
What should you check before starting to work with hand-held power tools?
Before starting work with hand-held electrical machines, hand-held lamps and power tools, the following should be carried out: - checking the completeness and reliability of fastening parts; - checking by external inspection the serviceability of the cable (cord) to the plug; integrity of the insulating parts of the body, handle and brush holder covers; availability protective covers and their serviceability; - checking the clear operation of the switch, - checking the operation at idle code; - for class I machines, checking the serviceability of the grounding circuits (between the machine body and the grounding contact of the plug); perform (if necessary) testing of the residual current device. Hand-held electrical machines, hand-held lamps, power tools and auxiliary equipment It is prohibited to issue them for work if they have defects.
How to route the wires or cables of portable power tools?
When using power tools, hand-held electrical machines and hand-held lamps, their wires or cables should be suspended whenever possible. Direct contact of wires or cables with hot, wet or oily surfaces or objects is not allowed. If any malfunctions are detected, work with manual electric machines, portable power tools and the lamps stop immediately.
Qualification groups for persons servicing electrical installations.
Group 1 is assigned to electrical personnel who have not passed the knowledge test in accordance with these rules, personnel servicing electrical installations, personnel working with power tools, drivers of vehicles and truck cranes, and cleaners of electrical installations. At the same time, persons of the 1st group do not have special electrical training, but have a basic understanding of the dangers of electric current and safety measures when working in the serviced area, electrical equipment, and installation. Persons of the 1st group must have practical familiarity with the rules of first aid.
The 2nd group is assigned to trainees of institutes, technical schools, technical and vocational schools, electricians, electric mechanics, signalmen, motor mechanics of electric motors, electric transport drivers, crane operators, electric welders, practical electricians (work experience of at least 1 month). Persons of the 2nd group must have: basic technical familiarity with electrical installations, a clear understanding of the dangers of electric current and approaching live parts, knowledge of basic precautions when working in electrical installations, practical familiarity with the rules of first aid.
The 3rd group is assigned to electricians, electricians, signalmen, and electrical operational personnel. substations, operational and repair personnel of electrical installations, trainees of institutes and technical schools, novice engineers and technicians, while work experience on electrical installations must be at least 6 months.
Persons of the 3rd group must have: basic knowledge of electrical engineering and familiarity with the design and maintenance of electrical installations, a clear understanding of the dangers when working in electrical installations, knowledge general rules safety precautions and rules of admission to work in electrical installations, knowledge of special safety rules for those types of work that are included in the duties of this person, the ability to supervise those working in electrical installations, knowledge of first aid rules and the ability to provide first aid to the victim.
The 4th group is assigned to electricians, electric mechanics, signalmen, operational personnel of power plants, operational and repair personnel of shop electrical installations, novice engineers and technicians, safety engineers (work experience in the previous group is at least 1 year). Persons of the 4th group must have: knowledge of electrical engineering in the scope of a specialized vocational school, a full understanding of the dangers when working in electrical installations, knowledge of these rules in full, as well as the rules for the use and testing of protective equipment used in electrical installations, knowledge of the installation so as to be able to understand freely which elements must be turned off to carry out work, find all these elements in nature and check their implementation and the necessary safety measures, the ability to organize safe work and supervise them in electrical installations with voltages up to 1000 V, knowledge of first aid rules and skills practically provide first aid to the victim (artificial respiration techniques, etc.).
Group 5 is assigned to electricians, electricians, craftsmen, technicians and trainee engineers (total work experience of at least 5 years, for persons with a 7th grade education and above who have undergone special training, as well as for persons who have graduated from vocational and technical schools, total experience at least 3 years). Craftsmen, technicians, engineers (with completed secondary or higher technical education) - total experience of at least 6 months. Age not younger than 19 – 21 years. Persons of the 5th group must have knowledge of the circuits and equipment of their site, a solid knowledge of these rules both in general and in special parts, as well as the rules for using and testing protective equipment used in electrical installations, a clear understanding of what caused the requirement or other item, ability to organize safe production work and supervise them in electrical installations of any voltage, knowledge of first aid rules and the ability to practically provide first aid (artificial respiration techniques, etc.), the ability to train personnel of other groups in safety rules and first aid.